Self-pumping hydropneumatic suspension strut

Abstract

A suspension strut includes an outer tube having a first filling opening and a second filling opening, an intermediate wall received in the outer tube and separating a high pressure chamber from a low pressure chamber, a working cylinder located concentrically inside the outer tube in the high pressure chamber, and a gas filled separating envelope located between the working cylinder and the outer tube for pressurizing damping medium in the high pressure chamber. An axially displaceable piston divides the working cylinder into a first working space and a second working space, the first working space being connected to the high pressure chamber. A hollow piston rod passing through the second working space transports damping medium from the low pressure chamber to the first working space. A pump rod fixed to the intermediate wall and received in the hollow piston rod forms a pump cylinder, the pump rod having a suction tube extending into the low pressure chamber for transporting damping fluid from the low pressure chamber to the piston rod. A gas lock device fitted to suction tube prevents flow of gas from the low pressure chamber into the suction tube when the low pressure chamber is filled with damping medium and gas, and the suspension strut is vertically oriented with the low pressure chamber at the top.

Description

[0001] 1. Field of the Invention[0002] The invention pertains to a self-pumping, hydropneumatic suspension strut with internal level control, especially for motor vehicles, having an outer tube having a first filling opening and a second filling opening, and an intermediate wall received in the outer tube, the intermediate wall separating a high pressure chamber from a low pressure chamber. The chambers each contain a damping medium, the first filling opening communicating with the low pressure chamber when the intermediate wall is not fully received in the outer tube and being closed by the intermediate wall when the intermediate wall is fully received in the outer tube. A working cylinder is located concentrically inside the outer tube in the high pressure chamber, and a gas filled separating envelope is located between the working cylinder and the outer tube for pressurizing the damping medium in the high pressure chamber. An axially displaceable piston divides the working cylind...

AI Technical Summary

Benefits of technology

[0008] It is advantageous here that the suspension strut can be filled in correspondence with its installation position and that it can also be mounted in the same position in the vehicle. It is also ensured here that the compressed gas cannot pass from the low-pressure chamber into the pump space during the filling process. This means not only that assembly can be carried out reliably but also that the suspension strut will function satisfactorily after installation.

[0009] In accordance with an essential feature, it is provided that one end of the pump rod projects into a cylindrical opening of a lock element and forms an opening before the complete axial insertion of the components. It is an advantage that, before final assembly, a flow connection is created, which is then tightly sealed after final assembly as a result of the axial insertion.

[0010] In accordance with another feature, it is provided that the lock element located on the end of the pump rod has a section of tubing, which extends into the area of the intermediate wall. The advantage here is that the tubing section, when installed in the appropriate position, always remains immersed in the damping medium of the low-pressure chamber, which prevents the compressed gas from escaping from the low-pressure chamber into the pump space.

[0011] In another embodiment, the pump rod is surrounded coaxially by a section of tubing and forms a channel, which extends from the end of the pump rod to a point near the intermediate wall. The advantage here is that the gas lock device can have a very simple design, in which merely an additional section of tubing is mounted coaxially around the end of the pump rod to form a flow connection, so that no compressed gas can pass into the pump space after installation in this design either.

Problems solved by technology

It is quite problematic to manufacture this type of design, however, because it must be done horizontally (FIGS. 3 and 4 of U.S. Pat. No. 6,648,309).

When the unit is to be filled with gas, the damping medium of the high-pressure chamber must be free to interchange with the damping medium of the low-pressure chamber via the open discharge bore so that the pressure can be equalized; during this process, the compressed gas may not pass from the low-pressure chamber into the pump space, for otherwise the pump itself will not be able to operate properly.

In addition, the assembly of a suspension strut of the horizontal type entails a considerable amount of work both to fill the unit with gas and to install the internal parts in the outer tube.

An assembly line for the production of suspension struts of the horizontal type therefore occupies a large amount of space.

Images